Process for tuning track currents



July 20 1926.

T. E. CLARK ET AL PROCESS FOR TUNING TRACK cunasms Fi led Noy. 4, K25

INVENTORS m if M Q'ZHTORNEY Patented July 20, 1926.

UNITED STATES OFFICE.

THOMAS E. CLARK AND JAMES E. CLARK, 033' DETROIT, MICHIGAN, ASSIGNOBS TOCONTINUOUS TRAIN CONTROL COBFORATION, 0F DETROIT, MICHIGAN, A CORPORA-TION OF MICHIGAN".

PROCESS FOR TUNING TRACK CUERENTS.

Application filed November 4, 1925. Serial No. 66,703.

This invention relates to the control of railway trains by means ofelectro-magnetic waves or flux in a wayside conductor whether it be thetrack rails or an independent conductor extending along the track, theutilization of the track rails as conductor being shown by ourco-pending application Serial Number 31,633, filed May 20, 1925, and theutilization of an independent conductor being shown in the Thomas E.Clark Patent No. 1,242,144, dated October 9, 1917.

In both of these systems, a transmitter of high-frequency high-potentialcurrent is positioned adjacent the end of each block into which thetrack is divided and the transmitting instrumentalities are constructedso as to embody adjustable devices which control the wave lengths ofthese cur rents so that the oscillating track circuits .will be in tunewith the collector coils mounted on the locomotive. We have found thatthe instrumentalities on the locomotives can easily be tuned toresonance with standard transmitting devices located at a centralstation such as a round house, and that the pitch of such locomotiveinstrumentalities will therefore be uniform. But we have found that whenthe track instrumentalities are tuned previously to being installedalong the track, the wave lengths of the currents propagated in therails will vary greatly by reason of the differences in impedance orconductivity of the rails and also because of the differences in thecharacter of the ballast, cross ties and the many other factors, bothknown and unknown.

It is therefore necessary to adjust or tune these track stations to apredetermined standard so that the current propagated in the trackconductors of each block or section will be the same as to wave lengthas that of all the other stations and that it will be of suflicientpower to properly afiect the instrumentalities on the locomotives in useon that particular stretch of track.

In the accompanying drawing, we have diagrammatically shown the tworails 1 and 2 of a track on which the trafiic is supposed to move in onedirection, that is, from right to left, these rails being divided intoblocks by the insulations 3. The transmitting or transforming mechanismcomprises a vacuum tube 38 having a plate 45, a grid 42 and a filament37. This filament is heated by a battery 13 whenever its circuit isclosed, which occurs when the rail block to which the relay 7 isconnected, is occupied, the re-- lay being short circuited thereby whichpermits its armature a to close the circuit over the wire 12, filament37, adjustable resistance 39, wires 14 and 27, armature a and wire 11.

The main oscillating circuit consists of the battery 36, wire 14,resistance 39, filament 37, the gap between it and the plate 45, wire48, coil 47, and wire 46 to the battery. The frequencies and wavelengths are controlled by the adjustable condenser 50 which shunts theplate coil 47 This battery 36 is usually termed the B battery and ispreferably of 350 voltage. Any other proper source of current may beemployed. The grid 42 connects to the circuit of the battery 13 by meansof the grid leak 44 and condenser 43 and the grid coil 40, and thiscircuit, together with the condenser 50, controls the production andrate of the oscillations.-

The loading coil 52 connects to the wires 5 and 6, which connect therelay 7 to the rails, by means of wires 32 and 33, a con denser 35 beingprovided to prevent the passage of direct signal currents and the shortcircuiting of the track circuit. This coil 52 and its connecting wires,the rails 1 and 2 of the controlled section between the wires 5 and 6and the condenser 20, and this condenser 20, constitute the outputoscillating circuit. The electro-magnetic waves of this circuit may beused to affect instrumentali ties on the locomotive passing over thistrack section and which are tuned to the frequency of said waves, atwhich time, the leading pilot axle of the locomotive and the wheelsthereon affect these wave lengths to some extent.

In order to render the wave lengths of the electro-magnetic currents inthe rails as nearly uniform as possible, the loading coil is formed tohave such an excess of millihenrys of inductance in proportion to theinductance of the rail section between the wires 5 and 6 and thecondenser 20, that the total inductance of the active oscillatingcircuit is not materially affected by the change in length of the railportion thereof by a locomotive moving along the section from thecondenser toward the insulations 3.

The lines of force seem to travel spirally around the rails 1 and 2 inopposite directions in zones of considerable diameter, these waves beingindicated by the lines 23. At the same time, other lines of force seemto pass from one rail to the other in the form of an arch.

Ne have shown a car 55 on the rails l and 2 and the deck of this carcarries a pair of collector coils 57 and 58 which are positioned so thattheir axes are substantially tangent to the spiral flux 23 of theelectromagnetic currents in the rails 1 and 2. A wave meter 59 on thiscar connects to one of these coils and to the adjustable condenser andis tuned to resonance with the standard or test track installation usedto standardize the locomotive installations.

The wave meter can be brought to the standard reading when the car is inthe track section of the track installation to be tested by adjustingthe condenser 50, and at the same time, the amp-meter 61 indicates thestrength of the current in this oscillating circuit. If the current islighter than necessary, the condenser 20 may be moved toward theinsulations 3, but if heavier, the condenser is moved fart-her away, forthe longest possible operative section is always desired for this workas it insures the operation of the instrumentalities on the locomotive.

Itis, of course, not necessary to transport the wave meter on a vehicle,as it may be transported in any other desired manner, and so long as astandard of comparison is employed by means of which the oscillatingcircuits of the track installations may be tuned to produceelectro-magnetic currents of the same wave lengths, any such standardmay be employed. But it must be a measuring device which can be readilytransport-- ed along the trackway and must embody means for so comparingeach transmitting station with a standard station that all willpropagate currents of the same wave lengths in the rails. Theseinstrumentalities may therefore be mounted on a locomotive and embodythe collector coils which constitute part of the control mechanismthereof.

We claim 1. The process of rendering uniform the wave lengths. ofelectro-magnetic currents propagated in wayside conductors for thecontrol of railway trains by track installa tions which embody resonantcircuits and adjustable condensers whereby the circuits may be tuned,which consists in positioning adjacent the several wayside circuits ofthe trackway consecutively a wave meter w rich has been tested by astandard oscillating circuit, and adjusting said condensers until theseveral track installations all propagate currents of the same wavelengths.

2. The process of rendering uniform the wave lengths of electro-magneticcurrents propagated in sections of railway tracks which are divided intoblocks by insulating joints, the sections being defined by theinsulation joints and by condensers connecting the rails, said currentsbeing produced for the control of railway trains by track installationswhich embody transformer coils, resonant circuits and condensers wherebythe circuits may be tuned, which process consists in positioning a wavemeter adjacent the rails of such track sections and adjusting saidcondensers of the several track sections until the indications of thewave meter at each section indicate the same current as that of astandard transmitting installation.

3. The process of rendering uniform the wave lengths of electro-magneticcurrents propagated in sections of railway tracks which are divided intoblocks by insulating joints, the sections being defined by theinsulation joints and by condensers connecting the rails, said currentsbeing produced for the control of railway trains by track installationswhich embody transformer coils, resonant circuits and condensers wherebythe circuits may be tuned, which process consists in positioning a wavemeter adjacent the rails of such track sections and adjusting saidcondensers of the several track sections until the indications of thewave meter at each section indicate the same current as that of astandard transmitting installation and in moving the condenser betweenthe rails along the track until the current so propagated is ofpredetermined strength.

THOMAS E. CLARK. JAMES E. CLARK.

